A currently accepted technique for assessing the severity of a stenosis in a blood vessel, including ischemia causing lesions, is fractional flow reserve (FFR). FFR is a calculation of the ratio of a distal pressure measurement (taken on the distal side of the stenosis) relative to a proximal pressure measurement (taken on the proximal side of the stenosis). FFR provides an index of stenosis severity that allows determination as to whether the blockage limits blood flow within the vessel to an extent that treatment is required. The normal value of FFR in a healthy vessel is 1.00, while values less than about 0.80 are generally deemed significant and require treatment. Common treatment options include percutaneous coronary intervention (PCI or angioplasty), stenting, or coronary artery bypass graft (CABG) surgery. As with all medical procedures, certain risks are associated with PCI, stenting, and CABG procedures.
The severity of a stenosis is sometimes observed visually and roughly estimated based on experience. For example, a patient's vasculature can be visualized using angiography. However, even with experience and expertise, the locations of stenoses in a vessel can be difficult to visualize in a grayscale angiographic image. The use of pressure data can improve the interpretation of information gleaned from an angiogram. Moreover, the severity of stenosis can also be better understood when efficiently visualized in relation to an angiographic image in connection with such data. Further, a more complete diagnosis of the patient can be made with intravascular imaging, such as intravascular ultrasound (IVUS) or optical coherence tomography (OCT). For example, in some instances intravascular imaging can be utilized to provide a cross-sectional image of the vessel and/or characterize the type(s) of tissue/plaque present.
In order for a surgeon to make a better-informed decision regarding treatment options, additional information about the characteristics of the vessel is desirable. However, medical personnel must balance the desire for additional information with the costs (e.g., money, time, resources, risks to the patient, etc.) of obtaining the additional information.
Accordingly, there remains a need for improved devices, systems, and methods for assessing the severity of a blockage in a vessel and, in particular, a stenosis in a blood vessel. Moreover, there remains a need for improved devices, systems, and methods that prompt a user to take particular action(s) to improve the diagnosis of a patient and, thereby, improve patient treatment outcomes.